Conventionally, when a continuity test or a performance test of a test target such as a semiconductor integrated circuit, and a liquid crystal panel is performed, a conductive contact probe providing the electrical connection between a test target and a signal processor having a semiconductor integrated circuit that outputs signals for testing is used. In order to perform an accurate continuity test or performance test, it is required to reliably perform the input and output of signals for testing through a contact probe. Herein, a contact probe repeatedly contacts with a test target such as a semiconductor integrated circuit and a liquid crystal display, and an electrical testing or measurement is performed. At that time, for example, when the contact probe is oxidized by the repeated use, the test results are affected.
Therefore, for the material used in a contact probe, high conductivity and corrosion resistance, and favorable oxidation resistance are required. For this requirement, in order to improve the oxidation resistance, for example, it can be mentioned to use a material in which tool steel has been plated with Au, however, the plating film is peeled off, and the background skin of the tool steel is exposed, as a result, the electric resistance is increased when the exposed material is contacted with a test target. Further, due to the exposure of the background skin of the tool steel, there may be a case where the background skin adheres to a test target as a foreign matter, and causes continuity failure. In order to eliminate the continuity failure, in the material to be used, it is most important to have the properties of low electric resistance and hardly-worn high hardness to suppress the wear of the contact probe itself even if the contact with a test target is performed in a repeated testing.
Among the materials having a property of high hardness, a copper (Cu)-beryllium (Be) alloy and a tungsten wire are mentioned as the metal material, however, are poor in the oxidation resistance to be used as a contact probe. A Cu—Be alloy, a tungsten wire, or the like in which metals other than noble metals are contained in large amount have high hardness, however, have a nature susceptible to oxidation, and when oxidation is caused, the conductivity is deteriorated, and the stable testing measurements cannot be performed. Therefore, an alloy having excellent oxidation resistance and conductivity, capable of being used for a long time, and having high conductivity, in which any of gold (Au), silver(Ag), platinum (Pt), palladium (Pd), and Cu is used as a main component, is used (see, for example, Patent Literatures 1 to 5).